I went back and watched the "Judge Roy Bean" temple run, and I did see the "DANGER" sign indeed. Good catch on that one!

I am surprised I didn't see that the first time around. And it makes sense too, since it was on the same day as "Bandit Queen".
As for "Hans Holbein", I didn't see the sign there in that episode after watching it just now. It looks like a panel similar to the DANGER sign is at the top. But I don't see any of the red lettering for the DANGER sign. And its the same way if you watch "The Metal Beard of the Egyptian Queen" (a later season three episode similar to "Bandit Queen") and the DANGER is not there either. It is unusual.